Here's the deal: you want your students to practice rounding off numbers so you give them one of these rando "worksheets" with lots of numbers saying "round off to the nearest ten," "round off to the nearest hundred," yadda yadda yadda and they do it and forget about it and it's just a superficial way to approach this important topic.
This takes the whole topic and reverses it, making it far more interesting and useful: each booklet starts by asking "When rounded off to the nearest thousand, it is 6,000..." Okay, that's an interesting clue: it means that the number has to be, what, anywhere between 5,500 and 6,499, which means it could be any one of 999 different numbers.
The mystery continues: "When rounded off to the nearest hundred, it is 5,600...." This narrows the number down to 99 different numbers. The next step is to narrow it down to ten numbers and then to use "digit sums" to locate the exact number.
Now, isn't that a lot more fun than just handing your kids a page of numbers to "round off?" Oh, and it gets your students to solve not one, not two, not three, but FOUR STEP PROBLEMS!
Also includes answer key, extensive instructions on how to use, as well as "do it yourself" activity so your students can make up their own mysteries!